1. Field of the Invention
This invention relates to a tape winder for winding a tape in a roll form and relates to a method of processing a tape wound in a roll form.
2. Description of the Related Art
In general, magnetic tapes, for example, of 12.7 mm (½ inch) width for linear or helical heads are widely used as external storage media for data backup for computers, etc. Such a magnetic tape has an overall thickness of no more than 10 μm and has a total of two or more magnetic layers (total thickness: no more than 0.3 μm) formed on top and back surfaces of a resin film of PET, PEN, aramid, etc.
Though such a magnetic tape is handled in a state of being wound around a tape reel, in the process of being wound around the tape reel by a winder or a drive, winding disturbance, with which the tape edges become misaligned, tends to occur. Winding disturbance becomes especially noticeable in the winding of magnetic tape at high speed. Since the tape edges are misaligned, a magnetic tape with which winding disturbance has occurred is readily damaged, for example, during its transport.
Such winding disturbance leads to the retention of winding defects during storage and causes degradation of the precision of tape travel within a drive and servo tracking errors. Thus to ensuring the required performance of a product, it is important to manufacture magnetic tapes, which can be wound around tape reels without giving rise to winding disturbance, provide good winding forms to be secured at the time of shipping, and do not undergo winding disturbance readily in drives.
It is known that when a magnetic tape is provided with a predetermined curved form, a good winding form is secured, tape travel is stabilized, and the servo tracking performance is improved. For example, when a magnetic tape is formed so as to be curved with respect to a reference line that joins the respective ends in the length direction, a good winding form is provided. On the other hand, when a fixed curving shape cannot be obtained, the winding form degrades.
Various technologies have thus been proposed to provide a tape with a predetermined curved form to obtain a good winding form.
For example, Japanese Laid-open Patent Application Publication No. 2003-346454 discloses, as a magnetic tape with which winding disturbance does not occur readily, a magnetic tape MT, which is curved in the width direction along its entire length as shown in FIG. 21A.
As shown in FIG. 21B, such a curved magnetic tape MT is wound around a tape reel R with its tape edge TE at the concave side contacting a flange surface FS. Since the magnetic tape MT is thus wound with a tape edge TE being set along flange surface FS, winding disturbance does not occur readily with magnetic tape MT.
A method of manufacturing this magnetic tape, disclosed in Japanese Laid-open Patent Application Publication No. 2003-346454, comprises: a winding step of winding the magnetic tape MT around a flange-less hub so that the tape becomes a bowl-like tape roll; and an aging step of providing the magnetic tape MT with a winding curl by applying an aging process to this bowl-like tape roll.
In the abovementioned winding step, the magnetic tape MT is wound around the hub while being pressed by a touch roller, the rotation axis of which is inclined at 0.02 to 2° with respect to the rotation axis of the hub, and the magnetic tape MT is thereby made a bowl-like tape roll around the hub. Also, in the abovementioned aging step, by the magnetic tape MT being provided with the abovementioned winding curl, magnetic tape MT becomes curved in its width direction.
As another method of providing magnetic tape MT with curvature, there is known, for example, a method, disclosed in Japanese Laid-open Patent Application Publication No. 2004-5774, wherein the magnetic tape is wound around a hub having different flexure strengths at one end face side and at the other end face side.
There is also known a method, disclosed in Japanese Laid-open Patent Application Publication No. Hei 9-138945, wherein a taper is formed in the hub of a tape reel and the magnetic tape is provided with a winding curl, with which winding disturbance does not occur readily, by means of this taper.
However, with the art disclosed in Japanese Laid-open Patent Application Publication No. 2003-346454, a wide (for example, a 12.7 mm (½ inch) wide) tape could not be provided adequately with a curvature by simple winding in some cases due to a high rigidity. Also, even if curvature was provided, the curvature was small. Furthermore, after being wound, the curvature of the tape tended to change readily with time and the securing of the quality at the time of shipping or the quality in the market after sales was difficult.
With the art disclosed in Japanese Laid-open Patent Application Publication No. 2004-5774 and Japanese Laid-open Patent Application Publication No. Hei 9-138945, as winding proceeds (as a wound roll becomes thicker), the effect of the taper diminishes due to air layers between the tape, thickness differences in the width direction of the tape, microscopic burrs at the edges of the magnetic tape, etc., and a winding curl could not be provided readily to the magnetic tape at the outer side of the wound roll. Also, due to manufacturing errors, there were cases where a curvature of the magnetic tape varies in a length direction and dispersion of the tape curvature occurs even at positions close to the hub.
Conventionally, a magnetic tape is manufactured by cutting a wide original magnetic tape fabric into a plurality of narrow bands and winding the cut bands around flange-less reels.
As a magnetic tape winder for this process, there is known a magnetic tape winder equipped with a touch roller, which presses the magnetic tape that is wound around a reel, in other words, a tape roll, and a restricting guide roller, which restricts wobbling in the width direction of the magnetic tape that is fed into the tape roll (see for example, Japanese Laid-open Patent Application Publication No. Sho 62-31645).
With this magnetic tape winder, the touch roller and the restricting guide roller are supported integrally by a plate-like member and the touch roller and the restricting guide roller are mounted, via the plate-like member, to the swinging end of a swinging arm. With this magnetic tape winder, by the swinging arm swinging towards the tape roll side, the touch roller and the restricting guide roller are pressed against the tape roll (surface of the magnetic tape) that gradually increases in diameter.
As a result, with this magnetic tape winder, falling off of the tape roll due to slipping of the wound magnetic tape with respect to itself and edge damage due to winding disturbance of the magnetic tape are avoided.
However, with the making of magnetic tapes higher in storage capacity recently, magnetic tapes are becoming thinner in thickness and since, and with the realization of high recording densities, the surfaces of magnetic tapes are being made smoother. Thus, the magnetic tapes are becoming lower in rigidity and the magnetic tape that is wound around a hub is becoming more slippery with respect to itself. Thus, with the magnetic tape winder of Japanese Laid-open Patent Application Publication No. Sho 62-31645, due to the lowering of the rigidity of the tape edges, the force of restricting the wobbling of the magnetic tape in the width direction by the restricting guide roller is becoming insufficient and winding disturbance of the magnetic tape is tending to occur readily.
Generally even if a heat treatment is applied to the magnetic tape (tape roll), with which such a winding disturbance has occurred, a good winding curl cannot be provided to the magnetic tape.
Also, since a magnetic tape slips readily with respect to itself, a magnetic tape that is being wound around a hub falls off readily from the hub. This trend is especially significant in a magnetic tape that is wound around a hub at high speed and has been a major impediment to improving the productivity of magnetic tapes.
There was thus a need for a tape winder that can prevent winding disturbance of a tape that is to be wound into a roll form and prevent the tape that has been wound around a hub from falling off the hub even if the tape is thin in thickness and the wound tape slips readily with respect to itself.
There was also a need for a tape processing method that enables a tape, with which winding disturbance does not occur readily and which is high in travel stability, to be manufactured by simple steps.